...and then pesky idle surges. According to Clarke's garage, Vacuum, dodgy throttle position switch or faulty Auxiliary air valve. I knew it wasn't the latter as it is brand new. The TPS I tested, no vacuum leaks... where to go from here?
I discovered that once warm, the throttle was not closing in the idle position thus not triggering the TPS whilst simultaneously not closing so that it was getting too much air at idle. The mechanism and return springs were all soft. I could not remove the butterfly as one of the little retaining screws was seized and subsequently rounded, That meant I could not strip it completely and clean it up properly, plus; the spindle is on 2 needle bearings to which I had no access.
Cue visit to Fleabay and a list of options for the 2.7 without any actual correct part numbers and not knowing if a readily available 2.5 throttle body would do. All that aside, I got this '2.7 throttle body' off fleabay from Status Porsche for a respectable £39.99 and then stripped it and cleaned it up a bit:

I noticed subtle differences with mine which suggests that there is a dedicated 2.7 throttle body and on the plus side, I got a round throttle cable wheel rather than the 'comma' shape thereby eliminating that blind spot. Either that or the round throttle wheel is an upgrade. It's all good. No idle surges.
